in your pictures of the manifold, I can see its a very straight design directly into the turbo, Im not sure how much stronger inconel is but that is a very long moment arm. I would be surprised if it doesnt start cracking heavily at the manifold flange. What have you done to support the turbos weight?
Also, do you have any trouble with intercooler air flow? How do you get enough flow through it apart from the addition of the fan? Is the body work enough to suck air through it?